date: do not allow "month #20" and such, closes 11356

function                                             old     new   delta
parse_datestr                                        906     961     +55

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/libbb/time.c b/libbb/time.c
index 82e6cb172..f9b8da0b3 100644
--- a/libbb/time.c
+++ b/libbb/time.c
@@ -184,6 +184,7 @@ void FAST_FUNC parse_datestr(const char *date_str, struct tm *ptm)
                         ptm->tm_year -= 1900; /* Adjust years */
                         ptm->tm_mon -= 1; /* Adjust month from 1-12 to 0-11 */
                 } else {
+ err:
                         bb_error_msg_and_die(bb_msg_invalid_date, date_str);
                 }
                 ptm->tm_sec = 0; /* assume zero if [.SS] is not given */
@@ -194,6 +195,19 @@ void FAST_FUNC parse_datestr(const char *date_str, struct tm *ptm)
                                 end = '\0';
                         /* else end != NUL and we error out */
                 }
+                /* Users were confused by "date -s 20180923"
+                 * working (not in the way they were expecting).
+                 * It was interpreted as MMDDhhmm, and not bothered by
+                 * "month #20" in the least. Prevent such cases:
+                 */
+                if (ptm->tm_sec > 60 /* allow "23:60" leap second */
+                 || ptm->tm_min > 59
+                 || ptm->tm_hour > 23
+                 || ptm->tm_mday > 31
+                 || ptm->tm_mon > 11 /* month# is 0..11, not 1..12 */
+                ) {
+                        goto err;
+                }
         }
         if (end != '\0') {
                 bb_error_msg_and_die(bb_msg_invalid_date, date_str);